Manchester United are facing a defensive crisis on the eve of their crucial Champions League trip to face Como.As the rain came down at Carrington, boss Michael Carrick observed a training session which featured just one senior centre back that has played this year in Harry Maguire.Lisandro Martinez, who was forced off at half-time away at Leeds United with a thigh issue, was held back from Tuesday’s session, putting his selection for the trip to Como in doubt.Leny Yoro sat the session out owing to his suspension after a red card in last week’s 2-0 defeat by Atletico Madrid. He is understood to be focusing on an individual training session today.Ayden Heaven, who also missed the trip to Leeds through illness, was another defender absent from training, and he remains touch-and-go to be on this afternoon’s flight to Italy.Luke Shaw and Patrick Dorgu remain longer term absentees, meaning Carrick is contending with five defensive injuries, all while Matthijs de Ligt, who did train, works his way back to full fitness having not played since November 2025. Lisandro Martinez was forced off at half-time of United’s 1-1 draw at Leeds on Sunday Marcus Rashford came on in the closing stages of the game but did not train this morningMarcus Rashford is another who is a major doubt to be on the flight as he continues to deal with a hip problem, which forced him to miss training.Kobbie Mainoo has not played since the 1-1 draw at home to Tottenham Hotspur and he remains sidelined.The big question now is who will be able to play in defence, especially given Carrick pivoted to a back five system for the 1-1 draw at Leeds.Diogo Dalot and Noussair Mazraoui represent the only options at full-back – Harry Amass and Jaydan Kamason both trained with the first team but are unlikely to be called upon – while Maguire’s centre back partner is at this stage up in the air. Academy centre back Dan Armer, who was on the bench in Madrid, was also in the session.United badly needed defensive reinforcements in the summer but dedicated their budget to bolstering the midfield following the sizeable exit of Casemiro.That gamble not to bolster the back-line is coming home to roost now with the Como trip a major test of the squad depth with Carrick potentially needing to thrust De Ligt back into the mix after 11 months out.